DIY fuzz face, which transistor?

[Off-Beat]

I want to build my own fuzz face, i have some germanium transistors to hand but i am not sure if they are the right ones to use. I have some BC142's, BC143, BC108. BC109, BF179.

Are any of these ok to use? Does one have to be npn and the other pnp?

Thanks

[J M Fahey]

All you mention are *silicon* .

Best way to know them is to download the datasheets ... and read them of course

If you have some Germaniums, just try them, if they work, they work.

Not in production for decades, so we are stuck with whatever is left.

[Off-Beat]

Yeah thats true, im pretty new to this game. Will the transitor determine the values of the the resistors and caps used? Or can i just get a fuzz face schematic and follow it using any of the above transistors?

[52 Bill]

Yeah thats true, im pretty new to this game. Will the transitor determine the values of the the resistors and caps used? Or can i just get a fuzz face schematic and follow it using any of the above transistors?

Historically there are two types of Fuzz Face circuits. The earliest was based on two PNP Germanium transistors that used a positive ground circuit. The later version was based on two NPN Silicon transistors that used a negative ground circuit. Besides the battery polarity, there was one resistor value that was different between the two circuits.

Some people prefer the sound of one version over the other and if you search on-line, I'm certain that you can find pages of discussions debating the merits of each circuit. I have built both versions many times over and find that each one has good and bad points, so you will probably have to judge for yourself.

[Off-Beat]

Thanks bill that helps, i guess i should build both just for the experience.

[pdf64]

You may find RG Keen's page on the FF interesting Technology of the Fuzz Face - Frame Definition

[Off-Beat]

Thanks!

[J M Fahey]

Yeah thats true, im pretty new to this game. Will the transitor determine the values of the the resistors and caps used? Or can i just get a fuzz face schematic and follow it using any of the above transistors?

It does not work that way, plus any series production would be impossible.

Normal design procedure is: designer thinks what he wants to achieve, balances possibilities because often there is many ways to skin a cat, builds prototypes, tweaks to taste, and finally reaches something he likes, then builds them.

He picks available and reasonable priced parts from catalogs and if possible sticks to them.

*IF* some becomes unavailable, he might search for an equivalence, a working replacement, and this might mean a couple values (mainly resistors) should be modified.

Sometimes unavailability is gross (Germanium out of production) and a major redesign might take place (going Silicon and inverting polarity count as such).

So in general it's more complex than just replacing a couple parts.